I watched an old guy die in a parking lot because of this. His hat blew off, he bent over to pick it up, and then fell forward onto his head. He died soon after. Now, he could have had some kind of other issues leading to this (he was elderly and had mobility issues). My wife parked while I ran over to render assistance, I called 911 while a military medic tried to revive him but it was too late.

So yeah, that can be enough (might have been a heart attack as a result of the shock, I am NOT a doctor, but he was gone by the time the ambulance arrived).

Also, one of the reasons street fighting is so dangerous has nothing to do with MMA dudes, it's when someone falls down and hits their head. This happens all the time. They sometimes die from the fall.